lastInsertId()导致程序崩溃

so I have this function below. At the very bottom I am returning $this->conn->lastInsertId(). If i'm not mistaken this should be correct.

FILE #1

 public function insertData($table, $qty, $data){                                                                
    $errors = "";                                                                                            
    $columns = $this->fetchColumnNames($table);                                                              
    $column_list = implode(', ', $columns);                                                                  
    $values = array_fill(0, $qty, '?');                                                                           
    $value_list = implode(', ', $values);                                                                         
    $q = "INSERT INTO $table ($column_list) VALUES ($value_list)";                                                
    $stmt = $this->conn->prepare($q);                                                                             
    for($i = 1; $i < $qty + 1; $i++){                                                                             
        foreach($data as $key => $val){                                                                           
            if($key == $columns[$i-1]){                                                                           
                try{                                                                                              
                    if(is_numeric($val)){                                                                         
                        $stmt->bindValue($i, $val, PDO::PARAM_INT);                                              
                    }else{                                                                                        
                        $stmt->bindValue($i, $val, PDO::PARAM_STR);                                               
                    }                                                                                             
                }catch(PDOException $e){                                                                          
                    print  $e->getMessage();                                                                      
                }                                                                                                 
            }                                                                                                     
        }                                                                                                         
    }                                                                                                             
    try{                                                                                                          
        $stmt->execute();                                                                                         
    }catch(PDOException $e){                                                                                      
        $errors .=  $e->getMessage();                                                                             
        print $errors;                                                                                            
    }                                                                                                             
    return $this->conn->lastInsertId();
}

So moving on to my main file, I have the following line of code

FILE #2

error_reporting(E_ALL);
ini_set('display_errors', 1);
include '../../inc/config.php';
include 'ProcessApplication/ProcessApplication.php';
include 'ProcessApplication/ProcessApplicationQuery.php';
$processor = new ProcessApplicationQuery($CONN);
$processor->insertData("full_application", 17, $general);
if($processor->getConn()){
    list($general, $phones) = $processor->processGeneralInfo($_REQUEST['general_information']);
    print $processor->insertData("full_application", 17, $general);
}

If I remove the return line from File #1 and just print in File #2 nothing happens, and the program inserts into the database like so. For some reason this return line is causing the entire program to fail and 404. It's very odd I have never had this occur, so why would this return line cause this error?

===UPDATE===

So even weirder I have added the follow items to my files FILE #1

 public function insertData($table, $qty, $data){                                                                
    $errors = "";                                                                                            
    $columns = $this->fetchColumnNames($table);                                                              
    $column_list = implode(', ', $columns);                                                                  
    $values = array_fill(0, $qty, '?');                                                                           
    $value_list = implode(', ', $values);                                                                         
    $q = "INSERT INTO $table ($column_list) VALUES ($value_list)";                                                
    $stmt = $this->conn->prepare($q);                                                                             
    for($i = 1; $i < $qty + 1; $i++){                                                                             
        foreach($data as $key => $val){                                                                           
            if($key == $columns[$i-1]){                                                                           
                try{                                                                                              
                    if(is_numeric($val)){                                                                         
                        $stmt->bindValue($i, $val, PDO::PARAM_INT);                                              
                    }else{                                                                                        
                        $stmt->bindValue($i, $val, PDO::PARAM_STR);                                               
                    }                                                                                             
                }catch(PDOException $e){                                                                          
                    print  $e->getMessage();                                                                      
                }                                                                                                 
            }                                                                                                     
        }                                                                                                         
    }                                                                                                             
    try{                                                                                                          
        $stmt->execute();                                                                                         
    }catch(PDOException $e){                                                                                      
        $errors .=  $e->getMessage();                                                                             
        print $errors;                                                                                            
    }                                                                                                             

}

public function getApplicationid(){
    $query = "SELECT id FROM eagle.full_application ORDER BY create_date DESC LIMIT 1";
    $id = null;
    foreach($this->conn->query($query) as $row){
        $id = $row['id'];
    }
    return $id;
}

FILE #2

error_reporting(E_ALL);
ini_set('display_errors', 1);
include '../../inc/config.php';
include 'ProcessApplication/ProcessApplication.php';
include 'ProcessApplication/ProcessApplicationQuery.php';
$processor = new ProcessApplicationQuery($CONN);
$processor->insertData("full_application", 17, $general);
if($processor->getConn()){
    list($general, $phones) = $processor->processGeneralInfo($_REQUEST['general_information']);
    $processor->insertData("full_application", 17, $general);
    echo $processor->getApplicationId();
}

I added a new method, and attempted to print it. I still get the error in which the files 404. It is really odd. I hope this helps out on the solution, because I am stumped.