Avoid accessing fields that are not guaranteed with api call

app/DTOs/OccurrenceDTO.php

@@ -8,8 +8,8 @@ class OccurrenceDTO
 {
     /**
      * @param  int  $occurrenceNo  oid — PBDB occurrence number
-     * @param  string  $acceptedName  tna — accepted taxon name
-     * @param  string  $acceptedRank  rnk — accepted taxonomic rank
+     * @param  string|null  $acceptedName  tna — accepted taxon name (absent for some PBDB records)
+     * @param  string|null  $acceptedRank  rnk — accepted taxonomic rank (absent for some PBDB records)
      * @param  string|null  $phylum  phl — phylum
      * @param  string|null  $class  cll — class
      * @param  string|null  $order  odl — order
@@ -31,8 +31,8 @@ class OccurrenceDTO
      */
     public function __construct(
         public readonly int $occurrenceNo,
-        public readonly string $acceptedName,
-        public readonly string $acceptedRank,
+        public readonly ?string $acceptedName,
+        public readonly ?string $acceptedRank,
         public readonly ?string $phylum,
         public readonly ?string $class,
         public readonly ?string $order,
@@ -104,14 +104,16 @@ private static function parseId(mixed $value): int
      */
     public static function fromArray(array $data): static
     {
-        $rawRank = $data['rnk'];
-        $acceptedRank = is_int($rawRank)
-            ? (self::RANK_LABELS[$rawRank] ?? (string) $rawRank)
-            : (string) $rawRank;
+        $rawRank = $data['rnk'] ?? null;
+        $acceptedRank = match (true) {
+            $rawRank === null => null,
+            is_int($rawRank) => self::RANK_LABELS[$rawRank] ?? (string) $rawRank,
+            default => (string) $rawRank,
+        };
 
         return new static(
             occurrenceNo: self::parseId($data['oid']),
-            acceptedName: $data['tna'],
+            acceptedName: $data['tna'] ?? null,
             acceptedRank: $acceptedRank,
             phylum: $data['phl'] ?? null,
             class: $data['cll'] ?? null,

docs/pbdb-api.md

@@ -236,7 +236,7 @@ The concrete implementation of `FossilOccurrenceServiceInterface`. Injected with
 
 A **readonly value object** representing a single fossil occurrence record. Created by `OccurrenceDTO::fromArray()` which maps PBDB's terse field codes (e.g. `oid`, `tna`, `phl`) to readable property names.
 
-All fields except `occurrenceNo`, `acceptedName`, `acceptedRank`, and `collectionNo` are nullable — PBDB does not guarantee every field is present in every record.
+All fields except `occurrenceNo` and `collectionNo` are nullable — PBDB does not guarantee every field is present in every record. `acceptedName` and `acceptedRank` are both nullable; when a taxon has not been entered into PBDB taxonomy (`tdf: 'taxon not entered'`), both `tna` and `rnk` are omitted. This is common in deep-time queries (e.g. Cambrian Seas and Great Dying presets).
 
 The `paleolat` / `paleolng` properties are only populated when `paleoloc` is in the `show` parameter.
 

resources/views/occurrences/show.blade.php

@@ -23,7 +23,7 @@ class="inline-flex items-center gap-1 text-sm text-muted hover:text-text transit
                 </h1>
 
                 <span class="inline-block rounded-full bg-accent-subtle border border-accent-muted px-2.5 py-0.5 text-xs font-medium text-accent mb-4">
-                    {{ ucfirst($occurrence->acceptedRank) }}
+                    {{ $occurrence->acceptedRank ? ucfirst($occurrence->acceptedRank) : 'Unknown' }}
                 </span>
 
                 @php

tests/Unit/DTOs/OccurrenceDTOTest.php

@@ -212,6 +212,26 @@ public function test_from_array_preserves_string_rank_unchanged(): void
         $this->assertSame('clade', $dto->acceptedRank);
     }
 
+    public function test_from_array_sets_null_rank_when_rnk_key_absent(): void
+    {
+        $record = $this->fullRecord;
+        unset($record['rnk']);
+
+        $dto = OccurrenceDTO::fromArray($record);
+
+        $this->assertNull($dto->acceptedRank);
+    }
+
+    public function test_from_array_sets_null_accepted_name_when_tna_key_absent(): void
+    {
+        $record = $this->fullRecord;
+        unset($record['tna']);
+
+        $dto = OccurrenceDTO::fromArray($record);
+
+        $this->assertNull($dto->acceptedName);
+    }
+
     public function test_from_array_maps_paleolat_and_paleolng(): void
     {
         $record = array_merge($this->fullRecord, [