Re-enable IDE0031 and adopt ?=

Author: YoshiRulz

.editorconfig

@@ -58,7 +58,7 @@ dotnet_diagnostic.IDE0029.severity = warning
 # Null check can be simplified
 dotnet_diagnostic.IDE0030.severity = warning
 # Use null propagation
-dotnet_diagnostic.IDE0031.severity = suggestion
+dotnet_diagnostic.IDE0031.severity = warning
 # Use auto property
 dotnet_diagnostic.IDE0032.severity = suggestion
 # Simplify default expression

src/BizHawk.Client.EmuHawk/MainForm.cs

@@ -3688,13 +3688,11 @@ private bool LoadRomInternal(string path, LoadRomArgs args, out bool failureIsFr
 				{
 					oaRetro.token.Path = loader.CanonicalFullPath;
 				}
-
-				if (oaOpenrom != null)
+				else if (oaOpenrom is not null)
 				{
 					oaOpenrom.Path = loader.CanonicalFullPath;
 				}
-
-				if (ioa is OpenAdvanced_MAME oaMame)
+				else if (ioa is OpenAdvanced_MAME oaMame)
 				{
 					oaMame.Path = loader.CanonicalFullPath;
 				}

src/BizHawk.Client.EmuHawk/tools/Lua/Libraries/TAStudioLuaLibrary.cs

@@ -425,10 +425,7 @@ public void SetBranchText(string text, int? index = null)
 			if (index != null)
 			{
 				var branch = Tastudio.CurrentTasMovie.Branches[index.Value];
-				if (branch != null)
-				{
-					branch.UserText = text1;
-				}
+				branch?.UserText = text1;
 			}
 			else
 			{

src/BizHawk.Client.EmuHawk/tools/SNES/SNESGraphicsDebugger.cs

@@ -816,12 +816,7 @@ private void paletteViewer_MouseClick(object sender, MouseEventArgs e)
 			bool valid = TranslatePaletteCoord(e.Location, out var pt);
 			if (!valid) return;
 			selectedColorNum = pt.Y * 16 + pt.X;
-
-			if (currTileDataState != null)
-			{
-				currTileDataState.Palette = currPaletteSelection.start;
-			}
-
+			currTileDataState?.Palette = currPaletteSelection.start;
 			SyncColorSelection();
 			InternalUpdateValues();
 		}

src/BizHawk.Client.EmuHawk/tools/TAStudio/BookmarksBranchesBox.cs

@@ -27,9 +27,7 @@ public partial class BookmarksBranchesBox : UserControl, IDialogParent
 		private BranchUndo _branchUndo = BranchUndo.None;
 
 		public void SetBackupMaxSteps(int value)
-		{
-			if (_backupBranch != null) _backupBranch.ChangeLog.MaxSteps = value;
-		}
+			=> _backupBranch?.ChangeLog.MaxSteps = value;
 
 		private enum BranchUndo
 		{
@@ -353,11 +351,7 @@ private void UndoBranchToolStripMenuItem_Click(object sender, EventArgs e)
 			else if (_branchUndo == BranchUndo.Text)
 			{
 				var branch = Branches.SingleOrDefault(b => b.Uuid == _backupBranch.Uuid);
-				if (branch != null)
-				{
-					branch.UserText = _backupBranch.UserText;
-				}
-
+				branch?.UserText = _backupBranch.UserText;
 				Tastudio.MainForm.AddOnScreenMessage("Branch Text Edit canceled");
 			}
 			else if (_branchUndo == BranchUndo.Remove)

src/BizHawk.Emulation.Cores/Computers/Commodore64/C64.Motherboard.cs

@@ -147,10 +147,8 @@ public Motherboard(C64 c64, C64.VicType initRegion, C64.BorderType borderType, C
 			CharRom = new Chip23128();
 			KernalRom = new Chip23128();
 
-			if (Cpu != null)
-				Cpu.DebuggerStep = Execute;
-			if (DiskDrive != null)
-				DiskDrive.DebuggerStep = Execute;
+			Cpu?.DebuggerStep = Execute;
+			DiskDrive?.DebuggerStep = Execute;
 		}
 
 		public int ClockNumerator { get; }

src/BizHawk.Emulation.Cores/Computers/SinclairSpectrum/ZXSpectrum.cs

@@ -135,16 +135,8 @@ public ZXSpectrum(
 				ay38912.PanningConfiguration = settings.AYPanConfig;
 				ay38912.Volume = settings.AYVolume;
 			}
-
-			if (_machine.BuzzerDevice != null)
-			{
-				_machine.BuzzerDevice.Volume = settings.EarVolume;
-			}
-
-			if (_machine.TapeBuzzer != null)
-			{
-				_machine.TapeBuzzer.Volume = settings.TapeVolume;
-			}
+			_machine.BuzzerDevice?.Volume = settings.EarVolume;
+			_machine.TapeBuzzer?.Volume = settings.TapeVolume;
 
 			DCFilter dc = new DCFilter(SoundMixer, 512);
 			ser.Register<ISoundProvider>(dc);

src/BizHawk.Emulation.Cores/Consoles/Nintendo/BSNES/SNESGraphicsDecoder.cs

@@ -386,7 +386,7 @@ public void RenderSpriteToScreen(
 					screen[dofs] = color;
 					Paletteize(screen, dofs, oamInfo.Palette * 16 + 128, 1);
 					Colorize(screen, dofs, 1);
-					if (spriteMap != null) spriteMap[dx, dy] = (byte)spritenum;
+					spriteMap?[dx, dy] = (byte) spritenum;
 				}
 			}
 		}

src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_Default.cs

@@ -66,10 +66,7 @@ public override void WriteMemory(ushort addr, byte value)
 			}
 			else
 			{
-				if (Core.cart_RAM != null)
-				{
-					Core.cart_RAM[addr - 0xA000] = value;
-				}
+				Core.cart_RAM?[addr - 0xA000] = value;
 			}
 		}
 

src/BizHawk.Emulation.Cores/Consoles/Nintendo/GBHawk/Mappers/Mapper_MBC6.cs

@@ -73,10 +73,7 @@ public override void WriteMemory(ushort addr, byte value)
 			}
 			else
 			{
-				if (Core.cart_RAM != null)
-				{
-					Core.cart_RAM[addr - 0xA000] = value;
-				}
+				Core.cart_RAM?[addr - 0xA000] = value;
 			}
 		}