Fix songs import when bmp not specified
Fix songs import when bmp not specified

rdsathene/SchoolIdolAPI,dburr/SchoolIdolAPI,SchoolIdolTomodachi/SchoolIdolAPI,dburr/SchoolIdolAPI,SchoolIdolTomodachi/SchoolIdolAPI,rdsathene/SchoolIdolAPI,rdsathene/SchoolIdolAPI,SchoolIdolTomodachi/SchoolIdolAPI,dburr/SchoolIdolAPI