[Backport release_3_5] check project scales and replace scale 0 with …

…scale 1 (#3820)

* check project scales and replace scale 0 with scale 1

* Apply suggestions from code review

Co-authored-by: mdouchin <mdouchin@3liz.com>

---------

Co-authored-by: rmartin <rmartin@3liz.com>
Co-authored-by: nworr <43475951+nworr@users.noreply.github.com>
Co-authored-by: mdouchin <mdouchin@3liz.com>

lizmap/modules/lizmap/classes/lizmapTiler.class.php

@@ -219,9 +219,7 @@ public static function getTileMatrixSetList($project, $wms_xml)
             $rootExtent[3] = $geoExtent[3];
         }
 
-        $scales = array_merge(array(), $project->getOption('mapScales'));
-        rsort($scales);
-
+        $scales = self::normalizeProjectScales($project);
         $projection = $project->getOption('projection');
 
         $tileMatrixSetList = array();
@@ -421,8 +419,7 @@ public static function getLayerTileInfo($layerName, $project, $wms_xml, $tileMat
             $rootExtent[3] = $geoExtent[3];
         }
 
-        $scales = array_merge(array(), $project->getOption('mapScales'));
-        rsort($scales);
+        $scales = self::normalizeProjectScales($project);
 
         $layers = $project->getLayers();
         $layer = $layers->{$layerName};
@@ -601,4 +598,16 @@ public static function getTileBbox($tileMatrixSet, $tileMatrixId, $tileRow, $til
 
         return (string) $minx.','.(string) $miny.','.(string) $maxx.','.(string) $maxy;
     }
+
+    private static function normalizeProjectScales($project)
+    {
+        $scales = array_merge(array(), $project->getOption('mapScales'));
+        if ($scales[0] == 0) {
+            $scales[0] = 1;
+            trigger_error('The minimum scale cannot have a value of 0, redefined as 1.', E_USER_NOTICE);
+        }
+        rsort($scales);
+
+        return $scales;
+    }
 }