internal/pkg: deduplicate unwrapped input errors

This avoids repeating errors belonging to multiple instances of the same artifact in different locations in memory.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/pkg/pkg_test.go

@@ -11,7 +11,6 @@ import (
 	"io"
 	"io/fs"
 	"log"
-	"maps"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -1979,6 +1978,22 @@ func TestInputError(t *testing.T) {
 			stub.UniqueError(0xbad09),
 			stub.UniqueError(0xbad0f),
 		}},
+
+		{"dedup", pkg.InputError{
+			makeIdent(0xff, 9): stub.UniqueError(0xbad09),
+			makeIdent(0xff, 9): stub.UniqueError(0xbad09),
+			makeIdent(0xff, 9): stub.UniqueError(0xbad09),
+			makeIdent(0xff, 0): stub.UniqueError(0xbad00),
+			makeIdent(0xff, 0): stub.UniqueError(0xbad00),
+			makeIdent(0xff, 1): stub.UniqueError(0xbad01),
+		}, `errors curing inputs:
+	_wAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: unique error 765184 injected by the test suite
+	_wEAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: unique error 765185 injected by the test suite
+	_wkAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA: unique error 765193 injected by the test suite`, []error{
+			stub.UniqueError(0xbad00),
+			stub.UniqueError(0xbad01),
+			stub.UniqueError(0xbad09),
+		}},
 	}
 	for _, tc := range testCases {
 		t.Run(tc.name, func(t *testing.T) {
@@ -1988,19 +2003,7 @@ func TestInputError(t *testing.T) {
 				t.Errorf("Error:\n%s\nwant\n%s", got, tc.want)
 			}
 
-			unwrap, unwrapM := tc.err.Unwrap(), make(map[error]struct{})
-			for _, a := range unwrap {
-				unwrapM[a] = struct{}{}
-			}
-
-			wantUnwrapM := make(map[error]struct{})
-			for _, a := range tc.unwrap {
-				wantUnwrapM[a] = struct{}{}
-			}
-
-			if len(unwrap) != len(unwrapM) ||
-				len(tc.unwrap) != len(wantUnwrapM) ||
-				!maps.Equal(unwrapM, wantUnwrapM) {
+			if unwrap := tc.err.Unwrap(); !reflect.DeepEqual(unwrap, tc.unwrap) {
 				t.Errorf("Unwrap: %#v, want %#v", unwrap, tc.unwrap)
 			}
 		})