babel-generator Invalid mapping when writing AST - abstract-syntax-tree

Question

While writing a plugin that injects code from another file ... another file is transformed and injected into the AST of the original file
astB = babel.transformFileSync(templatename, { plugins:plugins, code:false});
after that, calling:
generate(ast, { sourceMaps: true, retainLines: false, quotes:"'"}, codes);
causes error
Error: Invalid mapping: {"generated":{"line":30,"column":0},"original":{"line":1,"column":0}}
at SourceMapGenerator_validateMapping [as _validateMapping] (node_modules\babel-generator\node_modules\source-map\lib\source-map-generator.js:289:13)
at SourceMapGenerator_addMapping [as addMapping] (node_modules\babel-generator\node_modules\source-map\lib\source-map-generator.js:101:12)
at Array.forEach (<anonymous>)
at SourceMap.get (node_modules\babel-generator\lib\source-map.js:49:25)
at Object.get [as map] (node_modules\babel-generator\lib\buffer.js:53:33)
at writeAst (test2.js:59:24)
at Object.<anonymous> (test2.js:55:1)
at Module._compile (module.js:635:30)
at Object.Module._extensions..js (module.js:646:10)
at Module.load (module.js:554:32)

Answer 1

It is not very obvious from the error, but the problem is that injected code called parser as part of the transformation, and did not provide file name.
changing the line with transform fixes the issue
adding parserOpts:{sourceFilename: templatename} the code becomes:
astB = babel.transformFileSync(templatename, {parserOpts:{sourceFilename: templatename}, plugins:plugins, code:false});