private void buildError(ResourceFile sourceFile, String err) {
		BuildError error = buildErrors.computeIfAbsent(sourceFile, BuildError::new);
		error.append(err);
	}
Append the given build error. 
@param sourceFile the file w/ errors 
@param err an error string
Ghidra/Features/Base/src/main/java/ghidra/app/plugin/core/osgi/GhidraSourceBundle.java