Expand tests on parser to acheive higher coverage and minor fixs (#212)

* Expand tests on parser to achieve higher coverage
* Delete unreachable branch
* Add fix for Node with leading comma
* Add fix for duplicate statement when invalid member def statement appears
* Add fix for unset end of kvp

Author: joewyz

src/main/java/software/amazon/smithy/lsp/syntax/Parser.java

@@ -55,7 +55,7 @@ Syntax.Node parseNode() {
                 int start = position();
                 do {
                     skip();
-                } while (!isWs() && !isNodeStructuralBreakpoint() && !eof());
+                } while (!isWs() && !isNodeStructuralBreakpoint() && !eof() && is(','));
                 int end = position();
                 Syntax.Node.Err err = new Syntax.Node.Err("unexpected token " + document.copySpan(start, end));
                 err.start = start;
@@ -310,7 +310,9 @@ private Syntax.Node.Err kvp(Syntax.Node.Kvps kvps, char close) {
             if (err != null) {
                 addError(err);
             }
-
+            if (kvp != null) {
+                setEnd(kvp);
+            }
             return nodeErr("expected value");
         }
 
@@ -810,7 +812,6 @@ private void member(Syntax.Statement.Block parent) {
                 addErr(position(), position(), "expected :");
                 if (isWs() || is('}')) {
                     setEnd(memberDef);
-                    addStatement(memberDef);
                     return;
                 }
             }
@@ -963,6 +964,7 @@ private Syntax.Ident ident() {
         } while (isIdentChar());
 
         int end = position();
+
         if (start == end) {
             addErr(start, end, "expected identifier");
             return Syntax.Ident.EMPTY;