"[object Object]" text rendered in slides with empty text runs

[Gabe-IncentFit]

Description

The PPTX preview is rendering the literal text [object Object] in slides where empty <a:t> (text) elements exist in the PPTX XML. This occurs when a text run (<a:r>) contains an empty text element.

Root Cause

The bug is in the text extraction code within the pptx-preview library (v1.0.2). When parsing PPTX XML, the library extracts text using:

t.text = Y.get(e, "a:t") || ""

The issue is that when an <a:t></a:t> element is empty, the Y.get helper function returns an object instead of an empty string or null. Since objects are truthy in JavaScript, the || "" fallback never triggers, and the object is stored as the text value.

Later, when rendering this text with s.innerHTML = i (where i = r.text), JavaScript's implicit string conversion turns the object into the literal string "[object Object]", which is then displayed in the slide.

Example XML

Here's the XML structure that triggers this bug:

<a:p>
  <a:r>
    <a:rPr lang="en-US" sz="2800" dirty="0">
      <a:solidFill>
        <a:srgbClr val="1F3864"/>
      </a:solidFill>
      <a:latin typeface="DM Sans"/>
      <a:ea typeface="DM Sans"/>
      <a:cs typeface="DM Sans"/>
    </a:rPr>
    <a:t></a:t>  <!-- Empty text element returns object instead of empty string -->
  </a:r>
  <a:endParaRPr lang="en-US" dirty="0"/>
</a:p>

Expected Behavior

Empty <a:t> elements should render as empty strings (no visible text).

Actual Behavior

Empty <a:t> elements render as the literal text [object Object].

Recommended Solution

Ensure the text value is always coerced to a string:

Option 1 - Explicit String conversion:

t.text = String(Y.get(e, "a:t") || "")

Option 2 - String concatenation:

t.text = (Y.get(e, "a:t") || "") + ""

Option 3 - Type checking:

var textValue = Y.get(e, "a:t");
t.text = typeof textValue === "string" ? textValue : "";

Any of these approaches will ensure that objects are converted to strings and empty/null values become empty strings.

Workaround

Until this is fixed, the workaround is to ensure PPTX files don't contain empty <a:t></a:t> elements. However, this is difficult to control as various PowerPoint operations can create these elements.

Screenshot

Additional Context

This issue is similar to the line break bug reported in issue #[number] where <a:br> elements render as "undefined". Both stem from the same underlying problem: the rendering code doesn't properly handle non-string values returned by the XML parser.

Environment

• Library: pptx-preview v1.0.2 (via @vue-office/pptx v1.0.1)
• Browser: [All browsers affected]
• PPTX format: Office Open XML (.pptx)