Enable nullability in Content.Shared (#3626)

* Enable nullability in Content.Shared

* Fix null errors in server

* aye github i swear on me mom

Content.Client/Construction/ConstructionMenuPresenter.cs

@@ -6,7 +6,6 @@ using Content.Client.GameObjects.EntitySystems;
 using Content.Client.UserInterface;
 using Content.Client.Utility;
 using Content.Shared.Construction;
-using Content.Shared.GameObjects.Components;
 using Content.Shared.GameObjects.Components.Interactable;
 using Robust.Client.Graphics;
 using Robust.Client.Placement;
@@ -18,7 +17,6 @@ using Robust.Shared.GameObjects;
 using Robust.Shared.IoC;
 using Robust.Shared.Localization;
 using Robust.Shared.Prototypes;
-using Robust.Shared.Utility;
 
 namespace Content.Client.Construction
 {
@@ -224,15 +222,21 @@ namespace Content.Client.Construction
             var startNode = graph.Nodes[prototype.StartNode];
             var targetNode = graph.Nodes[prototype.TargetNode];
 
-            var path = graph.Path(startNode.Name, targetNode.Name);
+            if (!graph.TryPath(startNode.Name, targetNode.Name, out var path))
+            {
+                return;
+            }
 
             var current = startNode;
-
             var stepNumber = 1;
 
             foreach (var node in path)
             {
-                var edge = current.GetEdge(node.Name);
+                if (!current.TryGetEdge(node.Name, out var edge))
+                {
+                    continue;
+                }
+
                 var firstNode = current == startNode;
 
                 if (firstNode)

Content.Client/GameObjects/Components/Atmos/GasAnalyzerMenu.cs

@@ -165,7 +165,7 @@ namespace Content.Client.GameObjects.Components.Atmos
                     TemperatureHelpers.KelvinToCelsius(state.Temperature))
             });
             // Return here cause all that stuff down there is gas stuff (so we don't get the seperators)
-            if (state.Gases.Length == 0)
+            if (state.Gases == null || state.Gases.Length == 0)
             {
                 return;
             }

Content.Client/GameObjects/Components/Construction/ConstructionGhostComponent.cs

@@ -27,8 +27,13 @@ namespace Content.Client.GameObjects.Components.Construction
 
             if (!_prototypeManager.TryIndex(Prototype.Graph, out ConstructionGraphPrototype? graph)) return;
             var startNode = graph.Nodes[Prototype.StartNode];
-            var path = graph.Path(Prototype.StartNode, Prototype.TargetNode);
-            var edge = startNode.GetEdge(path[0].Name);
+
+            if (!graph.TryPath(Prototype.StartNode, Prototype.TargetNode, out var path) ||
+                !startNode.TryGetEdge(path[0].Name, out var edge))
+            {
+                return;
+            }
+
             edge.Steps[0].DoExamine(message, inDetailsRange);
         }
     }

Content.Client/GameObjects/EntitySystems/DragDropSystem.cs

@@ -20,6 +20,7 @@ using Robust.Shared.Localization;
 using Robust.Shared.Log;
 using Robust.Shared.Maths;
 using Robust.Shared.Prototypes;
+using Robust.Shared.Utility;
 using DrawDepth = Content.Shared.GameObjects.DrawDepth;
 
 namespace Content.Client.GameObjects.EntitySystems
@@ -217,8 +218,11 @@ namespace Content.Client.GameObjects.EntitySystems
             {
                 return false;
             }
+
+            DebugTools.AssertNotNull(_dragger);
+
             // still in range of the thing we are dragging?
-            if (!_interactionSystem.InRangeUnobstructed(_dragger, _dragDropHelper.Dragged))
+            if (!_interactionSystem.InRangeUnobstructed(_dragger!, _dragDropHelper.Dragged))
             {
                 return false;
             }