Typo in file extension does not result in error

| | |

|:---|:---|

|**_F´ Version_**| v3.4.3-117-g65b9e4d9d |

|**_Affected Component_**| build system |

---

## Problem Description



I created a file with the extension `.fp` instead of `.fpp` and added it to SOURCE_FILES in a module.



```

set(SOURCE_FILES

  "${CMAKE_CURRENT_LIST_DIR}/mymodule.hpp"

  "${CMAKE_CURRENT_LIST_DIR}/mymodule.fp"

)

```



Since `mymodule.fp` is not processed, I expect to get an error in this case. The presence of unrecognized source code is likely not intended, and catching it would help avoid mistakes. (This is most applicable when using a custom autocoder.)



## Context / Environment



Execute `fprime-util version-check` and share the output.



```

Operating System: Linux

CPU Architecture: x86_64

Platform: Linux-5.15.153.1-microsoft-standard-WSL2-x86_64-with-glibc2.34

Python version: 3.9.18

CMake version: 3.26.5

Pip version: 21.2.3

Pip packages:

    fprime-tools==3.4.5a1

    fprime-gds==3.4.4a3

    fprime-fpp-*==2.2.0a5

```



## How to Reproduce



1. Create a new file with the extension `.fp` and add it to an existing `SOURCE_FILES` list.

2. Try to build the project.

3. Notice that the project does not error out.



## Expected Behavior



An error should be reported explaining that the file extension cannot be recognized.

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