fix parsing of 'string<>' type

It used to think it was optional because it ends up being merged with
'mixed<>' which is implicitly optional, and we weren't explicitly setting
optional=false.

packages/realm/src/schema/normalize.ts

@@ -151,7 +151,7 @@ export function normalizePropertyType(type: string, allowObjectType = true): Obj
     return {
       type: "list",
       objectType: item.type === "object" ? item.objectType : item.type,
-      optional: item.type === "object" ? false : item.optional,
+      optional: item.type === "object" ? false : !!item.optional,
     };
   } else if (type.endsWith("<>")) {
     assert(allowObjectType, "Expected no 'objectType' in property schema, when using '<>' shorthand");
@@ -161,7 +161,7 @@ export function normalizePropertyType(type: string, allowObjectType = true): Obj
     return {
       type: "set",
       objectType: item.type === "object" ? item.objectType : item.type,
-      optional: item.type === "object" ? true : item.optional,
+      optional: item.type === "object" ? true : !!item.optional,
     };
   } else if (type.endsWith("{}")) {
     assert(allowObjectType, "Expected no 'objectType' in property schema, when using '{}' shorthand");
@@ -171,7 +171,7 @@ export function normalizePropertyType(type: string, allowObjectType = true): Obj
     return {
       type: "dictionary",
       objectType: item.type === "object" ? item.objectType : item.type,
-      optional: item.type === "object" ? true : item.optional,
+      optional: item.type === "object" ? true : !!item.optional,
     };
   } else if (type.endsWith("?")) {
     return {
@@ -183,6 +183,8 @@ export function normalizePropertyType(type: string, allowObjectType = true): Obj
       return { type, objectType: "mixed", optional: true };
     } else if (type === "set") {
       return { type, objectType: "mixed", optional: true };
+    } else if (type === "mixed") {
+      return {type, optional: true};
     } else {
       // This type is directly mappable, so it can't be the name a user defined object schema.
       return { type };

packages/realm/src/tests/schema-normalization.test.ts

@@ -35,6 +35,14 @@ describe("normalizePropertySchema", () => {
     expect(result.optional).equals(false);
   });
 
+  it("transforms a string declaring a set of strings", () => {
+    const result = normalizePropertySchema("prop", "string<>");
+    expect(result.name).equals("prop");
+    expect(result.type).equals("set");
+    expect(result.objectType).equals("string");
+    expect(result.optional).equals(false);
+  });
+
   it("transforms a string declaring a list of optional strings", () => {
     const result = normalizePropertySchema("prop", "string?[]");
     expect(result.name).equals("prop");