fix: Remove deprecation marks when formatting output for the `console` command. (#38676)

This change introduces handling of deprecation marks to resolve the linked issue, where the `console` command would panic when displaying a deprecated field, either directly, as part of a whole resource, or when referenced within a resource/local/etc.

Deprecation marks aren't used to change how values are rendered, but they need to be removed before we use the cty library to get string representations of values.

I decided to only remove marks in the context of a deprecation mark being present; if a different type of mark is added in future then the engineer implementing it will need to make an explicit decision about how it should be handled in the context of `console`. If that isn't done then the panic from the cty library will re-appear.

.changes/v1.15/BUG FIXES-20260603-172507.yaml

@@ -0,0 +1,5 @@
+kind: BUG FIXES
+body: 'console: Fixed a panic caused by evaluating an expression involving deprecated values'
+time: 2026-06-03T17:25:07.111161+01:00
+custom:
+    Issue: "38676"

internal/repl/format.go

@@ -20,12 +20,21 @@ func FormatValue(v cty.Value, indent int) string {
 	if !v.IsKnown() {
 		return "(known after apply)"
 	}
+
+	// Any marks on the value must either be used to return
+	// early or be removed. In future marks may used to cause
+	// values to be annotated, but the mark will still need to be
+	// removed before we can get a string representation of the value.
 	if marks.Has(v, marks.Sensitive) {
 		return "(sensitive value)"
 	}
 	if marks.Has(v, marks.Ephemeral) {
 		return "(ephemeral value)"
 	}
+	if marks.Has(v, marks.Deprecation) {
+		// Mark doesn't impact formatting, so remove to unblock normal formatting below
+		v, _ = v.Unmark()
+	}
 	if v.IsNull() {
 		ty := v.Type()
 		switch {

internal/repl/format_test.go

@@ -181,6 +181,10 @@ EOT_`,
 			cty.StringVal("an ephemeral value").Mark(marks.Ephemeral),
 			"(ephemeral value)",
 		},
+		{
+			cty.StringVal("I'm a deprecated string value").Mark(marks.Deprecation),
+			`"I'm a deprecated string value"`, // We don't render deprecated values differently, but we need to ensure the deprecation mark doesn't interfere with formatting
+		},
 	}
 
 	for _, test := range tests {