Fix config defaults

For some reason, when a string config option isn't specified it gets a
default value of `""`, so when we checked the new config option, the
empty string value would get chosen instead. So I added a default of
null for the old options, and I also switched the existing defaults to
the new options, choosing the old options first if they're present.

Author: milesziemer

package.json

@@ -108,7 +108,7 @@
                 "smithyLsp.version": {
                     "scope": "window",
                     "type": "string",
-                    "default": "0.6.0",
+                    "default": null,
                     "description": "Version of the Smithy Language Server (see https://github.com/smithy-lang/smithy-language-server).",
                     "deprecationMessage": "Use smithy.server.version instead."
                 },
@@ -121,7 +121,7 @@
                         "DANGER",
                         "ERROR"
                     ],
-                    "default": "WARNING",
+                    "default": null,
                     "description": "Minimum severity of Smithy validation events to display in the editor.",
                     "deprecationMessage": "Use smithy.server.diagnostics.minimumSeverity instead."
                 },
@@ -150,10 +150,12 @@
                 },
                 "smithy.server.executable": {
                     "type": "string",
+                    "default": null,
                     "description": "Executable to run the Smithy Language Server. Can be the executable name if it is on your PATH, or an absolute path to the executable."
                 },
                 "smithy.server.version": {
                     "type": "string",
+                    "default": "0.6.0",
                     "description": "Version of the Smithy Language Server to use. Ignored if smithy.server.executable is provided."
                 },
                 "smithy.server.diagnostics.minimumSeverity": {

src/config.ts

@@ -1,7 +1,7 @@
 import * as vscode from 'vscode';
 
 export function getServerDiagnosticsMinimumSeverity(): string | undefined {
-    return getConfig('server.diagnostics.minimumSeverity') ?? getOldConfig('diagnostics.minimumSeverity');
+    return getOldOrNewConfig('diagnostics.minimumSeverity', 'server.diagnostics.minimumSeverity');
 }
 
 export function getServerOnlyReloadOnSave(): boolean | undefined {
@@ -13,7 +13,11 @@ export function getServerExecutable(): string | undefined {
 }
 
 export function getServerVersion(): string {
-    return getConfig('server.version') ?? getOldConfig('version');
+    return getOldOrNewConfig('version', 'server.version');
+}
+
+function getOldOrNewConfig<T>(oldKey: string, newKey: string): T | undefined {
+    return getOldConfig(oldKey) || getConfig(newKey);
 }
 
 function getConfig<T>(key: string): T | undefined {