Internal Compiler Errors in Unity

UnityErrors.cs

public static class ExtensionTests {

  public static void Test(this object target, float a, float b = 1, float c = 2, float d = 3) { }
  
}

object target = null;

// Compiles
target.Test(0);
target.Test(0, b: 2);
target.Test(0, d:2 , c: 2);

target.Test(b:2, a:0);
target.Test(b: 2, a: 3, d: 2);

// Does not compile
/*
target.Test(c: 2, a: 0);  
target.Test(d: 2, a: 0);
target.Test(d:2, b:2, a:3);
target.Test(b: 2, d: 2, a: 3);
*/




// The error message:
/*
Unhandled Exception: Mono.CSharp.InternalErrorException: Internal error
  at Mono.CSharp.MethodGroupExpr.IsApplicable (Mono.CSharp.ResolveContext ec, Mono.CSharp.Arguments& arguments, Int32 arg_count, System.Reflection.MethodBase& method, System.Boolean& params_expanded_form) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.MethodGroupExpr.OverloadResolve (Mono.CSharp.ResolveContext ec, Mono.CSharp.Arguments& Arguments, Boolean may_fail, Location loc) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.ExtensionMethodGroupExpr.ResolveOverloadExtensions (Mono.CSharp.ResolveContext ec, Mono.CSharp.Arguments& arguments, Mono.CSharp.NamespaceEntry ns, Location loc) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.ExtensionMethodGroupExpr.OverloadResolve (Mono.CSharp.ResolveContext ec, Mono.CSharp.Arguments& arguments, Boolean may_fail, Location loc) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.Invocation.DoResolveOverload (Mono.CSharp.ResolveContext ec) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.Invocation.DoResolve (Mono.CSharp.ResolveContext ec) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.Expression.Resolve (Mono.CSharp.ResolveContext ec, ResolveFlags flags) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.Expression.Resolve (Mono.CSharp.ResolveContext ec) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.ExpressionStatement.ResolveStatement (Mono.CSharp.BlockContext ec) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.StatementExpression.Resolve (Mono.CSharp.BlockContext ec) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.Block.Resolve (Mono.CSharp.BlockContext ec) [0x00000] in <filename unknown>:0 
  at Mono.CSharp.ToplevelBlock.Resolve (Mono.CSharp.FlowBranching parent, Mono.CSharp.BlockContext rc, Mono.CSharp.ParametersCompiled ip, IMethodData md) [0x00000] in <filename unknown>:0 

Internal compiler
*/