[Swift-user] Error: Attempted to close nonexistent channel buffers

[Allen, M. David]

Hello,

I'm just getting started with Swift, and trying to program a fairly
trivial sample to get started.

My swiftscript fails with the message:
"Execution failed:
        grep started
Attempted to close nonexistent channel buffers"
 
Can anyone point me to the documentation that describes such errors?
This is referring to a spot in my code that is executing a very vanilla
grep operation.  My input file is just 14 lines long, and this error
consistently happens towards the end of the overall workflow execution.
 
The code:
 
type blog {
    string name;
    string feedURL;
}
 
type file { }
 
(file headlines) getHeadlines(blog b) {
        app {
                feeder @b.feedURL stdout=@filename(headlines);
        }
}
 
(file results[]) processBlogs(blog blogs[]) {
 
        foreach blog el, index in blogs {
                results[index] = getHeadlines( el ) ;
        }
}
 
(string matches) findSingleMatch(file input, string searchTerm) {
        app {
                grep "-i" searchTerm @filename(input) stdout=@matches;
        }
}
 
(file matches) findMatches(file inputs[], string searchTerm) {
        string final;
 
        foreach input, index in inputs {
                string intermed = findSingleMatch(input, searchTerm);
                final = strcat(final, intermed);
        }
 
        matches = dumpString(final);
}
 
(int retVal) debug(string m) {
        app {
                echo m ;
        }
}
 
(file t) dumpString(string m) {
    app {
        echo m stdout=@filename(t);
    }
}
 
blog blogs[]  <csv_mapper; file="blogs.csv", delim=",", header="true">;
file output[] <simple_mapper;
prefix="output/blogHeadlines",suffix=".txt">;
file final <simple_mapper; prefix="output/result", suffix=".txt">;
 
output = processBlogs(blogs);
final = findMatches(output, "ARG 0");

Any help would be greatly appreciated.
--
M. David Allen
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