I have something like this:
WARNING in C:/Data/.../letsTest.jsx There are multiple modules with names that only differ in casing. This can lead to unexpected beh
Eventually, I found the answer. It was a Windows issue. It was necessary to change the absolute path in C:\Data...\r1HeadLearning.js from
c:\Data\...\letsTest.jsx
to
C:\Data\...\letsTest.jsx