Make sure FrameCount is 1 when reading a MagickImage (#1761).

Author: dlemstra

src/Magick.NET/MagickImage.cs

@@ -7374,6 +7374,8 @@ private MagickReadSettings CreateReadSettings(IMagickReadSettings<QuantumType>?
         else
             newReadSettings = new MagickReadSettings(readSettings);
 
+        newReadSettings.ForceSingleFrame();
+
         return newReadSettings;
     }
 

src/Magick.NET/Settings/MagickReadSettings.cs

@@ -125,6 +125,12 @@ public bool UseMonochrome
     /// </summary>
     public uint? Width { get; set; }
 
+    internal void ForceSingleFrame()
+    {
+        FrameCount = 1;
+        ApplyFrame();
+    }
+
     private static string GetDefineKey(IDefine define)
     {
         if (define.Format == MagickFormat.Unknown)