fail early if both incremental and filter_stdlibs (#800)

Author: baggepinnen

src/PackageCompiler.jl

@@ -760,6 +760,9 @@ function create_app(package_dir::String,
                     sysimage_build_args::Cmd=``,
                     include_transitive_dependencies::Bool=true)
     warn_official()
+    if filter_stdlibs && incremental
+        error("must use `incremental=false` to use `filter_stdlibs=true`")
+    end
     # We call this at the very beginning to make sure that the user has a compiler available. Therefore, if no compiler 
     # is found, we throw an error immediately, instead of making the user wait a while before the error is thrown.
     get_compiler_cmd()