Add expected ranges to year, month, day decoding errors

Author: andrewheard

FirebaseVertexAI/Sources/Types/Internal/ProtoDate.swift

@@ -97,7 +97,12 @@ extension ProtoDate: Decodable {
     if let year = try container.decodeIfPresent(Int.self, forKey: .year), year != 0 {
       guard year >= 1 && year <= 9999 else {
         throw DecodingError.dataCorrupted(
-          .init(codingPath: [CodingKeys.year], debugDescription: "Invalid year: \(year)")
+          DecodingError.Context(
+            codingPath: [CodingKeys.year],
+            debugDescription: """
+            Invalid year: \(year); must be from 1 to 9999, or 0 for a date without a specified year.
+            """
+          )
         )
       }
       self.year = year
@@ -108,7 +113,13 @@ extension ProtoDate: Decodable {
     if let month = try container.decodeIfPresent(Int.self, forKey: .month), month != 0 {
       guard month >= 1 && month <= 12 else {
         throw DecodingError.dataCorrupted(
-          .init(codingPath: [CodingKeys.month], debugDescription: "Invalid month: \(month)")
+          DecodingError.Context(
+            codingPath: [CodingKeys.month],
+            debugDescription: """
+            Invalid month: \(month); must be from 1 to 12, or 0 for a year date without a \
+            specified month and day.
+            """
+          )
         )
       }
       self.month = month
@@ -119,7 +130,12 @@ extension ProtoDate: Decodable {
     if let day = try container.decodeIfPresent(Int.self, forKey: .day), day != 0 {
       guard day >= 1 && day <= 31 else {
         throw DecodingError.dataCorrupted(
-          .init(codingPath: [CodingKeys.day], debugDescription: "Invalid day: \(day)")
+          DecodingError.Context(
+            codingPath: [CodingKeys.day],
+            debugDescription: """
+            Invalid day: \(day); must be from 1 to 31, or 0 for a date without a specified day.
+            """
+          )
         )
       }
       self.day = day