`write()` does not write text-content to the file.

Bug Description

write() does not write text-content to the file.

Steps to reproduce

u=mopen("SuperBlockPlot.cosf", "w"); 
write(u, ["this is first line";"second line"], "(a)"),
write(u, "this is third line", "(a)"),
mclose(u);

What is the expected correct behavior?

File is filled with three lines.

Error log