Trying to synthesize the generated Verilog with yosys fails:
$ yosys -p "read_verilog TangNano9k.v; synth_gowin -json TangNano9k.json"
...
2.2.2. Analyzing design hierarchy..
Top module: \TangNano9k
Used module: \PatternExample
Used module: \HVSync
Used module: \HdmiTx
Used module: \Oser10Module
Used module: \Rgb2Tmds
Used module: \TMDSEncoder
Used module: \Gowin_rPLL
ERROR: Module `\OSER10' referenced in module `\Oser10Module' in cell `\osr10' is not part of the design.
Trying to synthesize the generated Verilog with yosys fails: