As -- -- said, your issue has been resolved
"If a static resource is not declared but is used then it does not given error at design time or in debug mode on both iPhone simulator or on physical device. However, in release from TestFlight it crashes app. Best way seems to be to use a third party error logger to quickly catch such errors at runtime in release."
(Refer to this issue- Missing StaticResource should throw exception also in Debug #15602)
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