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diff --git a/src/main/java/sevenUnits/unit/LoadingException.java b/src/main/java/sevenUnits/unit/LoadingException.java
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+++ b/src/main/java/sevenUnits/unit/LoadingException.java
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+/**
+ * Copyright (C) 2024, 2025 Adrien Hopkins
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+package sevenUnits.unit;
+
+import java.nio.file.Path;
+import java.util.Optional;
+
+/**
+ * An exception that occurred when loading a file. This wrapper class adds more
+ * info about the error.
+ *
+ * @author Adrien Hopkins
+ * @since 2024-08-22
+ * @since v1.0.0
+ */
+public final class LoadingException extends RuntimeException {
+	/** The type of file that was being loaded. */
+	public enum FileType {
+		@SuppressWarnings("javadoc")
+		UNIT, @SuppressWarnings("javadoc")
+		DIMENSION
+	}
+
+	private static final long serialVersionUID = -8167971828216907607L;
+
+	private final long lineNumber;
+	private final String line;
+	private final Optional<Path> file;
+
+	private final FileType fileType;
+
+	private final RuntimeException problem;
+
+	/**
+	 * Create a LoadingException from some information, without a file.
+	 *
+	 * @param lineNumber line number error happened on
+	 * @param line       text of invalid line
+	 * @param fileType   type of file
+	 * @param problem    problem, as an Exception
+	 */
+	public LoadingException(long lineNumber, String line, FileType fileType,
+			RuntimeException problem) {
+		super(problem);
+		this.lineNumber = lineNumber;
+		this.line = line;
+		this.file = Optional.empty();
+		this.fileType = fileType;
+		this.problem = problem;
+	}
+
+	/**
+	 * Create a LoadingException from some information, with a file.
+	 *
+	 * @param lineNumber line number error happened on
+	 * @param line       text of invalid line
+	 * @param file       file error happened on
+	 * @param fileType   type of file
+	 * @param problem    problem, as an Exception
+	 */
+	public LoadingException(long lineNumber, String line, Path file,
+			FileType fileType, RuntimeException problem) {
+		super(problem);
+		this.lineNumber = lineNumber;
+		this.line = line;
+		this.file = Optional.of(file);
+		this.fileType = fileType;
+		this.problem = problem;
+	}
+
+	/** @return the file this error happened in, if there is one */
+	public Optional<Path> file() {
+		return this.file;
+	}
+
+	/** @return type of file that this error happened in */
+	public FileType fileType() {
+		return this.fileType;
+	}
+
+	@Override
+	public String getMessage() {
+		return this.file
+				.map(f -> String.format(
+						"Error parsing line %d of %s file '%s' (\"%s\"): %s",
+						this.lineNumber, this.fileType.toString().toLowerCase(), f,
+						this.line, this.problem))
+				.orElse(String.format(
+						"Error parsing line %d of %s stream (\"%s\"): %s",
+						this.lineNumber, this.fileType.toString().toLowerCase(),
+						this.line, this.problem));
+	}
+
+	/** @return text of line that caused this error */
+	public String line() {
+		return this.line;
+	}
+
+	/** @return number of line that caused this error */
+	public long lineNumber() {
+		return this.lineNumber;
+	}
+
+	/** @return the error, as an exception */
+	public RuntimeException problem() {
+		return this.problem;
+	}
+}