fix crash/exit instead of returning error for unsupported mappers

[Morilli]

Should fix TASEmulators/BizHawk#4186.

BizHawk-side diff:

diff --git a/quicknes/bizinterface.cpp b/quicknes/bizinterface.cpp
index 81249c60d..29a7cbfee 100644
--- a/quicknes/bizinterface.cpp
+++ b/quicknes/bizinterface.cpp
@@ -37,10 +37,9 @@ QN_EXPORT void qn_delete(quickerNES::Emu *e)
 	free(e);
 }
 
-QN_EXPORT const char *qn_loadines(quickerNES::Emu *e, const void *data, int length)
+QN_EXPORT const char *qn_loadines(quickerNES::Emu *e, const uint8_t *data, int length)
 {
-	e->load_ines((const uint8_t*)data);
-	return 0;
+	return e->load_ines(data);
 }
 
 QN_EXPORT const char *qn_set_sample_rate(quickerNES::Emu *e, int rate)