Refactor config updates (#13802)

# Description
This PR standardizes updates to the config through a new
`UpdateFromValue` trait. For now, this trait is private in case we need
to make changes to it.

Note that this PR adds some additional `ShellError` cases to create
standard error messages for config errors. A follow-up PR will move
usages of the old error cases to these new ones. This PR also uses
`Type::custom` in lots of places (e.g., for string enums). Not sure if
this is something we want to encourage.

# User-Facing Changes
Should be none.

tests/hooks/mod.rs

@@ -441,7 +441,7 @@ fn err_hook_wrong_env_type_1() {
     let actual_repl = nu!(nu_repl_code(inp));
     dbg!(&actual_repl.err);
 
-    assert!(actual_repl.err.contains("unsupported_config_value"));
+    assert!(actual_repl.err.contains("Type mismatch"));
     assert_eq!(actual_repl.out, "");
 }
 
@@ -458,7 +458,7 @@ fn err_hook_wrong_env_type_2() {
 
     let actual_repl = nu!(nu_repl_code(inp));
 
-    assert!(actual_repl.err.contains("type_mismatch"));
+    assert!(actual_repl.err.contains("Type mismatch"));
     assert_eq!(actual_repl.out, "");
 }
 
@@ -480,7 +480,7 @@ fn err_hook_wrong_env_type_3() {
 
     let actual_repl = nu!(nu_repl_code(inp));
 
-    assert!(actual_repl.err.contains("unsupported_config_value"));
+    assert!(actual_repl.err.contains("Type mismatch"));
     assert_eq!(actual_repl.out, "");
 }
 
@@ -503,7 +503,7 @@ fn err_hook_non_boolean_condition_output() {
 
     let actual_repl = nu!(nu_repl_code(inp));
 
-    assert!(actual_repl.err.contains("unsupported_config_value"));
+    assert!(actual_repl.err.contains("Type mismatch"));
     assert_eq!(actual_repl.out, "");
 }
 
@@ -526,7 +526,7 @@ fn err_hook_non_condition_not_a_block() {
 
     let actual_repl = nu!(nu_repl_code(inp));
 
-    assert!(actual_repl.err.contains("unsupported_config_value"));
+    assert!(actual_repl.err.contains("Type mismatch"));
     assert_eq!(actual_repl.out, "");
 }
 
@@ -548,7 +548,7 @@ fn err_hook_parse_error() {
 
     let actual_repl = nu!(nu_repl_code(inp));
 
-    assert!(actual_repl.err.contains("unsupported_config_value"));
+    assert!(actual_repl.err.contains("source code has errors"));
     assert_eq!(actual_repl.out, "");
 }
 

tests/repl/test_config.rs

@@ -119,7 +119,7 @@ fn mutate_nu_config_plugin() -> TestResult {
 
 #[test]
 fn reject_nu_config_plugin_non_record() -> TestResult {
-    fail_test(r#"$env.config.plugins = 5"#, "should be a record")
+    fail_test(r#"$env.config.plugins = 5"#, "Type mismatch")
 }
 
 #[test]
@@ -151,7 +151,7 @@ fn mutate_nu_config_plugin_gc_default_stop_after_negative() -> TestResult {
             $env.config.plugin_gc.default.stop_after = -1sec
             $env.config.plugin_gc.default.stop_after
         "#,
-        "must not be negative",
+        "expected a non-negative duration",
     )
 }