HTTP/3: generate more H3_FRAME_UNEXPECTED. As per quic-http-34, these are the cases when this error should be generated: If an endpoint receives a second SETTINGS frame on the control stream, the endpoint MUST respond with a connection error of type H3_FRAME_UNEXPECTED SETTINGS frames MUST NOT be sent on any stream other than the control stream. If an endpoint receives a SETTINGS frame on a different stream, the endpoint MUST respond with a connection error of type H3_FRAME_UNEXPECTED. A client MUST NOT send a PUSH_PROMISE frame. A server MUST treat the receipt of a PUSH_PROMISE frame as a connection error of type H3_FRAME_UNEXPECTED; see Section 8. The MAX_PUSH_ID frame is always sent on the control stream. Receipt of a MAX_PUSH_ID frame on any other stream MUST be treated as a connection error of type H3_FRAME_UNEXPECTED. Receipt of an invalid sequence of frames MUST be treated as a connection error of type H3_FRAME_UNEXPECTED; see Section 8. In particular, a DATA frame before any HEADERS frame, or a HEADERS or DATA frame after the trailing HEADERS frame, is considered invalid. A CANCEL_PUSH frame is sent on the control stream. Receiving a CANCEL_PUSH frame on a stream other than the control stream MUST be treated as a connection error of type H3_FRAME_UNEXPECTED. The GOAWAY frame is always sent on the control stream.

/* XPM */
static char * nginx_xpm[] = {
"16 16 2 2",
/* colors */
"   c none",
"GG c #009900",
/* pixels */
"                                ",
"        GGGGGGGGGGGGGGGG        ",
"        GGGGGGGGGGGGGGGG        ",
"      GGGGGGGGGGGGGGGGGGGG      ",
"      GGGGGG        GGGGGG      ",
"    GGGGGG            GGGGGG    ",
"    GGGGGG                      ",
"  GGGGGG      GGGGGGGGGGGGGGGG  ",
"  GGGGGG    GGGGGGGGGGGGGGGGGG  ",
"    GGGGGG    GGGGGGGGGGGGGG    ",
"    GGGGGG            GGGGGG    ",
"      GGGGGG        GGGGGG      ",
"      GGGGGGGGGGGGGGGGGGGG      ",
"        GGGGGGGGGGGGGGGG        ",
"        GGGGGGGGGGGGGGGG        ",
"                                "
};