Either the Canvas size is too small or too much of the image is masked out.

img

#GovRptWordCloudv5.py
import jieba
import wordcloud
import imageio
mask=imageio.imread("fivestar.png")
f=open("新时代中国特色社会主义.txt","r",encoding="utf-8")
t=f.read()
f.close()
ls=jieba.lcut(t)
ls = [word for word in ls if len(word)>1]# 该条主要是为了排除一个字符以下的词，没有这条文本将会分出都是单字。
txt=" ".join(ls)
w=wordcloud.WordCloud(font_path="msyh.ttc",mask=mask,\
     width=1000,height=700,background_color="white",\
    )
w.generate(txt)
w.to_file("grwordcloud6.png")

错误提示是说，你的画布尺寸与掩膜图像尺寸不能匹配，可能是你的画布尺寸太大，而mask太小。无法画出图，将函数中height和width设置小些再试试。
使用默认大小即可：

import jieba
import wordcloud
import imageio
mask = imageio.imread("star.jpg")
f = open("r25.txt", "r", encoding="utf-8")
t = f.read()
f.close()
ls = jieba.lcut(t)
# 该条主要是为了排除一个字符以下的词，没有这条文本将会分出都是单字。
ls = [word for word in ls if len(word) > 1]
txt = " ".join(ls)
w = wordcloud.WordCloud(font_path="msyh.ttc", mask=mask,background_color="white",
                        )
w.generate(txt)
w.to_file("grwordcloud6.png")

img