msi: A custom action dll failing to load is not a fatal error.

dlls/msi/custom.c

@@ -424,10 +424,7 @@ static MSIBINARY *create_temp_binary( MSIPACKAGE *package, LPCWSTR source, BOOL
     /* keep a reference to prevent the dll from being unloaded */
     if (dll && !(binary->module = LoadLibraryW( tmpfile )))
     {
-        ERR("failed to load dll %s (%u)\n", debugstr_w( tmpfile ), GetLastError() );
-        DeleteFileW( tmpfile );
-        msi_free( binary );
-        return NULL;
+        WARN( "failed to load dll %s (%u)\n", debugstr_w( tmpfile ), GetLastError() );
     }
     binary->source = strdupW( source );
     binary->tmpfile = strdupW( tmpfile );
@@ -720,8 +717,8 @@ static DWORD ACTION_CallDllFunction( const GUID *guid )
     hModule = LoadLibraryW( dll );
     if (!hModule)
     {
-        ERR("failed to load dll %s (%u)\n", debugstr_w( dll ), GetLastError() );
-        return r;
+        WARN( "failed to load dll %s (%u)\n", debugstr_w( dll ), GetLastError() );
+        return ERROR_SUCCESS;
     }
 
     proc = strdupWtoA( function );