fix: initialize nil patterns map in extractPlaceID to prevent panic

The patterns map was declared but never initialized before being
written to in the sync.Once block, causing a nil map assignment
panic at runtime.

Added unit tests for extractPlaceID covering various URL formats.

Author: aurbina83

gmaps/reviews.go

@@ -206,6 +206,7 @@ func extractPlaceID(mapURL string) (string, error) {
 			hexMatchPattern,                          // Hex format place ID
 		}
 
+		patterns = make(map[string]*regexp.Regexp)
 		for _, p := range avail {
 			patterns[p] = regexp.MustCompile(p)
 		}

gmaps/reviews_test.go

@@ -0,0 +1,58 @@
+package gmaps
+
+import (
+	"testing"
+)
+
+func Test_extractPlaceID(t *testing.T) {
+	tests := []struct {
+		name    string
+		url     string
+		want    string
+		wantErr bool
+	}{
+		{
+			name:    "standard hex format with exclamation prefix",
+			url:     "https://www.google.com/maps/place/Joe's+Pizza+Broadway/@40.7546795,-73.9870291,17z/data=!4m7!3m6!1s0x89c259ab3c1ef289:0x3b67a41175949f55!8m2!3d40.7546795!4d-73.9870291!16s%2Fg%2F11bw4ws2mt?hl=en&entry=ttu",
+			want:    "0x89c259ab3c1ef289:0x3b67a41175949f55",
+			wantErr: false,
+		},
+		{
+			name:    "place_id query parameter format",
+			url:     "https://www.google.com/maps/place/Joe's+Pizza/@40.7546795,-73.9870291,17z?place_id=ChIJDdnwdv0y5xQRRytw1ihZQeU&hl=en",
+			want:    "ChIJDdnwdv0y5xQRRytw1ihZQeU",
+			wantErr: false,
+		},
+		{
+			name:    "full place URL with data and hex ID",
+			url:     "https://www.google.com/maps/place/Coffee+Project+New+York/data=!4m7!3m6!1s0x89c2599b5a24d7fd:0x9e354f6cf514b9fc!8m2!3d40.7270884!4d-73.989382!16s%2Fg%2F11c3svpqld!19sChIJ_dckWptZwokR_LkU9WxPNZ4",
+			want:    "0x89c2599b5a24d7fd:0x9e354f6cf514b9fc",
+			wantErr: false,
+		},
+		{
+			name:    "maps search URL (no place ID)",
+			url:     "https://www.google.com/maps/search/pizza+in+Brooklyn+NY",
+			want:    "",
+			wantErr: true,
+		},
+		{
+			name:    "empty URL",
+			url:     "",
+			want:    "",
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := extractPlaceID(tt.url)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("extractPlaceID() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if got != tt.want {
+				t.Errorf("extractPlaceID() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}