Fix #11417: Allow EVENT_MENU_MAIN plugin events to return null

A plugin may decide not to print a menu entry via the EVENT_MENU_MAIN
event hook based on which project is currently selected. Therefore the
return value from EVENT_MENU_MAIN should be checked to make sure it
isn't null. If it is null, then don't print anything in the menu.

Signed-off-by: David Hicks <hickseydr@optusnet.com.au>

core/html_api.php

@@ -735,7 +735,9 @@ function print_menu() {
 				if( is_array( $t_callback_menu_options ) ) {
 					$t_menu_options = array_merge( $t_menu_options, $t_callback_menu_options );
 				} else {
-					$t_menu_options[] = $t_callback_menu_options;
+					if ( !is_null( $t_callback_menu_options ) ) {
+						$t_menu_options[] = $t_callback_menu_options;
+					}
 				}
 			}
 		}
@@ -783,7 +785,9 @@ function print_menu() {
 				if( is_array( $t_callback_menu_options ) ) {
 					$t_menu_options = array_merge( $t_menu_options, $t_callback_menu_options );
 				} else {
-					$t_menu_options[] = $t_callback_menu_options;
+					if ( !is_null( $t_callback_menu_options ) ) {
+						$t_menu_options[] = $t_callback_menu_options;
+					}
 				}
 			}
 		}
@@ -908,7 +912,9 @@ function print_summary_submenu() {
 			if( is_array( $t_callback_menu_options ) ) {
 				$t_menu_options = array_merge( $t_menu_options, $t_callback_menu_options );
 			} else {
-				$t_menu_options[] = $t_callback_menu_options;
+				if ( !is_null( $t_callback_menu_options ) ) {
+					$t_menu_options[] = $t_callback_menu_options;
+				}
 			}
 		}
 	}
@@ -1004,7 +1010,9 @@ function print_manage_menu( $p_page = '' ) {
 			if( is_array( $t_callback_menu_options ) ) {
 				$t_menu_options = array_merge( $t_menu_options, $t_callback_menu_options );
 			} else {
-				$t_menu_options[] = $t_callback_menu_options;
+				if ( !is_null( $t_callback_menu_options ) ) {
+					$t_menu_options[] = $t_callback_menu_options;
+				}
 			}
 		}
 	}
@@ -1121,7 +1129,9 @@ function print_account_menu( $p_page = '' ) {
 			if( is_array( $t_callback_menu_options ) ) {
 				$t_menu_options = array_merge( $t_menu_options, $t_callback_menu_options );
 			} else {
-				$t_menu_options[] = $t_callback_menu_options;
+				if ( !is_null( $t_callback_menu_options ) ) {
+					$t_menu_options[] = $t_callback_menu_options;
+				}
 			}
 		}
 	}
@@ -1182,7 +1192,9 @@ function print_summary_menu( $p_page = '' ) {
 			if( is_array( $t_callback_menu_options ) ) {
 				$t_menu_options = array_merge( $t_menu_options, $t_callback_menu_options );
 			} else {
-				$t_menu_options[] = $t_callback_menu_options;
+				if ( !is_null( $t_callback_menu_options ) ) {
+					$t_menu_options[] = $t_callback_menu_options;
+				}
 			}
 		}
 	}