NRE in 6.3.0-preview5 on .NET Core with parameterized StartsWith()

[roji]

When using EF6 6.3.0-preview5-19254-05 in an application targeting netcoreapp3.0, an NRE is produced from the following code:

var x = "X";
var blogs = ctx.Blogs.Where(b => b.Name.StartsWith(x)).ToList();

Stack trace:

Unhandled Exception: System.NullReferenceException: Object reference not set to an instance of an object.
   at System.Linq.Expressions.Compiler.LambdaCompiler.EmitMethodCall(Expression obj, MethodInfo method, IArgumentProvider methodCallExpr, CompilationFlags flags)
   at System.Linq.Expressions.Compiler.LambdaCompiler.EmitExpression(Expression node, CompilationFlags flags)
   at System.Linq.Expressions.Compiler.LambdaCompiler.EmitInstance(Expression instance, Type& type)
   at System.Linq.Expressions.Compiler.LambdaCompiler.EmitMemberExpression(Expression expr)
   at System.Linq.Expressions.Compiler.LambdaCompiler.EmitExpression(Expression node, CompilationFlags flags)
   at System.Linq.Expressions.Compiler.LambdaCompiler.EmitLambdaBody(CompilerScope parent, Boolean inlined, CompilationFlags flags)
   at System.Linq.Expressions.Compiler.LambdaCompiler.EmitLambdaBody()
   at System.Linq.Expressions.Compiler.LambdaCompiler.Compile(LambdaExpression lambda)
   at System.Data.Entity.Core.Objects.ELinq.QueryParameterExpression.EvaluateParameter(Object[] arguments)
   at System.Data.Entity.Core.Objects.ELinq.ELinqQueryState.GetExecutionPlan(Nullable`1 forMergeOption)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<>c__DisplayClass41_0.<GetResults>b__1()
   at System.Data.Entity.Core.Objects.ObjectContext.ExecuteInTransaction[T](Func`1 func, IDbExecutionStrategy executionStrategy, Boolean startLocalTransaction, Boolean releaseConnectionOnSuccess)
   at System.Data.Entity.SqlServer.DefaultSqlExecutionStrategy.Execute[TResult](Func`1 operation)
   at System.Data.Entity.Core.Objects.ObjectQuery`1.<System.Collections.Generic.IEnumerable<T>.GetEnumerator>b__31_0()
   at System.Data.Entity.Internal.LazyEnumerator`1.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Test.Program.Main(String[] args) in /home/roji/projects/Test/Program.cs:line 19

[ajcvickers]

/cc @bricelam

[bricelam]

I'm still digging into this, but it looks like a bug in .NET Core's expression compiler. It will affect any query that translates to LIKE. Trying to create a simple repro...