Fix crash on asm gen when no settings file exists

README.md

@@ -30,9 +30,9 @@ as well as many less-common ones.
   processor status flags are tracked, allowing identification of branches
   that are always/never taken, accurate cycle count listings, and correct
   analysis of 65816 code with variable-width registers.
-- Easy generation of assembly source code in popular formats (currently
-  cc65 and Merlin 32). Cross-assemblers can be invoked from the GUI to
-  verify correctness.
+- Easy generation of assembly source code for popular cross-assemblers
+  (currently cc65, 64tass, and Merlin 32). Cross-assemblers can be invoked
+  from the GUI to verify correctness.
 - Symbols and constants are provided for ROM and operating system entry
   points on several popular systems.
 - Project files are designed for sharing and collaboration.</li>

SourceGen/AsmGen/AssemblerConfig.cs

@@ -68,14 +68,17 @@ private static string GetSettingName(AssemblerInfo.Id id) {
 
         /// <summary>
         /// Creates a populated AssemblerConfig from the app settings for the specified ID.
+        /// If the assembler hasn't been configured yet, the default configuration object
+        /// will be returned.
         /// </summary>
         /// <param name="settings">Settings object to pull the values from.</param>
         /// <param name="id">Assembler ID.</param>
-        /// <returns>The AssemblerConfig, or null if not configured.</returns>
+        /// <returns>The AssemblerConfig.</returns>
         public static AssemblerConfig GetConfig(AppSettings settings, AssemblerInfo.Id id) {
             string cereal = settings.GetString(GetSettingName(id), null);
             if (string.IsNullOrEmpty(cereal)) {
-                return null;
+                IAssembler asm = AssemblerInfo.GetAssembler(id);
+                return asm.GetDefaultConfig();
             }
 
             JavaScriptSerializer ser = new JavaScriptSerializer();