Fallback to a standard font if a font-file entry doesn't contain a Stream (issue 18941)

The PDF document is clearly corrupt, since it has /FontFile2 entries that are Dictionaries which obviously isn't correct.
While there's obviously no guarantee that things will look perfect this way, actually rendering the text at all should be an improvement in general.

src/core/evaluator.js

@@ -4436,6 +4436,16 @@ class PartialEvaluator {
     let glyphScaleFactors = null;
     let systemFontInfo = null;
     if (fontFile) {
+      if (!(fontFile instanceof BaseStream)) {
+        const msg = `Font file should be a Stream in "${fontName.name}".`;
+
+        if (!this.options.ignoreErrors) {
+          throw new FormatError(msg);
+        }
+        warn(msg);
+        fontFile = new NullStream();
+      }
+
       if (fontFile.dict) {
         const subtypeEntry = fontFile.dict.get("Subtype");
         if (subtypeEntry instanceof Name) {

test/pdfs/issue18941.pdf.link

@@ -0,0 +1 @@
+https://github.com/user-attachments/files/17473385/21_10_2024_FAMI.INVERSION.SAS_901060703_inicial.pdf

test/test_manifest.json

@@ -2352,6 +2352,15 @@
     "lastPage": 3,
     "type": "eq"
   },
+  {
+    "id": "issue18941",
+    "file": "pdfs/issue18941.pdf",
+    "md5": "6288e69c1dd240859c1d49c22a53a5c7",
+    "rounds": 1,
+    "link": true,
+    "lastPage": 1,
+    "type": "eq"
+  },
   {
     "id": "f1040",
     "file": "pdfs/f1040.pdf",