Fix crash on some projects opening

BUG: 409477
1 job for master in 17 minutes and 26 seconds (queued for 4 minutes and 18 seconds)
Status Job ID Name Coverage
failed #68445
linux kf5-qt5 qt5.12


Name Stage Failure
linux kf5-qt5 qt5.12 Build
      |                                                                                                                                                                                                 ^~~~~~~~~~~~~
make[2]: *** [src/CMakeFiles/kdenliveLib.dir/build.make:2633: src/CMakeFiles/kdenliveLib.dir/timeline2/model/builders/meltBuilder.cpp.o] Error 1
make[1]: *** [CMakeFiles/Makefile2:1286: src/CMakeFiles/kdenliveLib.dir/all] Error 2
make: *** [Makefile:160: all] Error 2
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ERROR: Job failed: exit code 1